The present invention relates to a system for displaying on a two-dimensional display current estimated from measurement of biomagnetism.
Weak magnetic fields generated in the heart and the brain have been measured and displayed recently by a superconducting quantum interference device (SQUID). These measurements are used to estimate the currents flowing through the heart or the nerves which give rise to these magnetic fields. Such bioelectric currents are considered to be current dipoles in which a current flows through a small distance. The position, direction, magnitude and depth from a body surface of such current dipoles need to be clearly displayed on a two-dimensional display.
Heretofore, only magnetic field components perpendicular to the body surface have been measured. These measurements have been made from above the heart by a SQUID flux meter. The position, magnitude and direction of the current dipole have also been estimated. As shown in FIG. 1, these are indicated on a two-dimensional display by an arrow 1 superimposed on an image (iso map) 2. The iso map 2 also shows constant magnetic field lines.
However, the arrow 1 does not indicate the depth from the body surface at which the current dipole exists. This makes diagnosis difficult with the conventional method.